The present invention generally relates to vehicle occupant sensing and, more particularly, relates to radar motion sensing to detect occupant movement in a vehicle.
There are situations where it is generally undesirable to leave a child, an elderly passenger, an unconscious passenger, or a pet in the passenger compartment of a vehicle for an extended period of time. This is especially true on a hot day when the inside vehicle temperature may become extremely high. It is therefore desirable to detect when an occupant may be trapped in the passenger compartment of a vehicle, or other compartments, such as the trunk compartment. In order to detect the presence of an occupant to thus reduce the risk to the occupant, it is desirable to provide for an occupant sensing system that detects the presence of the occupant in the vehicle.
In the past, radar motion sensing systems have been employed in vehicles to detect substantial movement of objects within the vehicle. In particular, vehicle security systems have employed radar motion sensing devices for detecting large movements within the vehicle such as entering or exiting of an occupant from the vehicle and movement applied to the vehicle from the outside typically, in an attempt to secure the vehicle against theft. While prior radar motion sensing systems have been used to detect large movements in a vehicle, the amount of movement detected is generally limited to rather significant movements of large objects. Conventional vehicle radar motion sensing approaches have not reliably provided the ability to sense the presence of a relaxed infant or an unconscious passenger within the vehicle.
Accordingly, it is therefore desirable to provide for a vehicle occupant sensing system that exhibits high sensitivity for sensing the presence of an occupant within the vehicle. In particular, it is desirable to provide for a vehicle occupant sensing system and method which detects small movement of an occupant, such as a relaxed infant or an unconscious passenger, within a compartment in the vehicle.
According to the teachings of the present invention, a motion detection system and method for detecting an occupant in a vehicle are provided which realizes enhanced sensitivity to detect small movement, such as movement caused by heartbeat and breathing of an occupant. According to one aspect of the present invention, the motion detection system for detecting an occupant in the vehicle includes a radar motion sensor located in a compartment of the vehicle. The radar motion sensor transmits and receives signals within the compartment and generates sensed signals. The motion detection system further includes a controller converting the sensed signals to a frequency domain. The controller further processes the frequency domain of sensed signals and determines the presence of movement of an occupant due to one of heartbeat and breathing of an occupant.
According to another aspect of the present invention, a method is provided for detecting an occupant in a vehicle. The method includes the steps of transmitting a radar signal within a compartment in a vehicle, receiving the transmit radar signals, and generating radar sensor output signals. The method also includes the steps of transforming the radar sensor output signals to a frequency domain, and processing the frequency domain of received radar sensor output signals within a frequency range. The method further includes the step of determining movement due to one of breathing and heartbeat of an occupant based on the processing. Accordingly, the motion detection system and method of the present invention provides enhanced sensitivity to detect very small movement within a vehicle so as to detect the presence of an occupant therein.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.